His victory in the election is 'almost a certainty'. [=it is nearly certain/definite that he will win the election]
It is difficult to say 'with certainty' [=in a certain or definite way] which of the plays was written first.
Scientists still do not know with any degree of 'certainty' why the disease spread so quickly.
(..) I'd like to know what Maya thinks. We're all incorporating her assessment into ours. A hundred percent he's there. Okay, fine, percent 'cause I know certainty freaks you guys out, but it's a hundred. They're all cowed. - What do you think of the girl? - I think she's fucking smart. (..)2012 Zero Dark Thirty
(..) Now I remember Iraq WMD, very clearly. I fronted that. And I can tell you the case for that, was much stronger than this case. A fucking "yes" or a "no". We don't deal in certainty, we deal in probability. And I'd say there's a percent probability he's there. I concur, percent. (..)2012 Zero Dark Thirty